I am thinking about getting a used Mac Pro (in addition to my current macbook). The early 2.0 GHz 2x2 cores can be found quite cheap. It looks like I could even get X5350 quad cores for reasonable money, meaning I could build an 8 cores 2.66 ( or 3.4 GHz with BSEL?) for less than 1500 . Is this a good idea or am I going to face problems and disillusion?